A colony of beagles with primary glaucoma has been established. Affected X affected matings have produced glaucomatous offspring. Clinical signs of glaucoma, observed in beagles 6 to 18 months of age, include buphthalmia, lens luxation, cataract formation, vitreous syneresis, retinal and optic disc degeneration. The disease will be documented by serial photography-external, goniscopic, slit lamp biomicroscopic, fundus and fluorescein angiography. The iridocorneal angles are open by goniscopy and further study will be conducted by light and electron microscopy. Water, corticosteroid and mydriatic provocative tests are under evaluation in the dogs. The various type of indentation and applanation tonometry will be compared in the dog. Aqueous outflow in glaucomatous beagles will be estimated by tonography and constant pressure perfusion. The effects of selected adrenergic, cholinergic and diuretic drugs will be evaluated in these dogs by applanation tonometry, tonography and constant pressure perfusion.